--- a/widget/cocoa/nsChildView.mm
+++ b/widget/cocoa/nsChildView.mm
@@ -1709,27 +1709,29 @@ bool nsChildView::PreRender(WidgetRender
   // compositing. That would make us unable to call postRender on it when the
   // composition is done, thus keeping the GL context locked forever.
   mViewTearDownLock.Lock();
 
   return true;
 }
 
 void nsChildView::PostRender(WidgetRenderingContext* aContext) {
-  auto compositingState = mCompositingState.Lock();
-  if (compositingState->mAsyncCATransactionsSuspended) {
-    // We should not trigger a CATransactions on this thread. Instead, let the
-    // main thread take care of calling ApplyChanges at an appropriate time.
-    compositingState->mNativeLayerChangesPending = true;
-  } else {
-    // Force a CoreAnimation layer tree update from this thread.
-    [NSAnimationContext beginGrouping];
-    mNativeLayerRoot->ApplyChanges();
-    compositingState->mNativeLayerChangesPending = false;
-    [NSAnimationContext endGrouping];
+  {  // scope for lock
+    auto compositingState = mCompositingState.Lock();
+    if (compositingState->mAsyncCATransactionsSuspended) {
+      // We should not trigger a CATransactions on this thread. Instead, let the
+      // main thread take care of calling ApplyChanges at an appropriate time.
+      compositingState->mNativeLayerChangesPending = true;
+    } else {
+      // Force a CoreAnimation layer tree update from this thread.
+      [NSAnimationContext beginGrouping];
+      mNativeLayerRoot->ApplyChanges();
+      compositingState->mNativeLayerChangesPending = false;
+      [NSAnimationContext endGrouping];
+    }
   }
   mViewTearDownLock.Unlock();
 }
 
 RefPtr<layers::NativeLayerRoot> nsChildView::GetNativeLayerRoot() { return mNativeLayerRoot; }
 
 static int32_t FindTitlebarBottom(const nsTArray<nsIWidget::ThemeGeometry>& aThemeGeometries,
                                   int32_t aWindowWidth) {